Biomedical subjects

Ling Chen

Publications and source records attributed to Ling Chen.

At least 91 records · Page 5Linked to original sources

PubMed2004

Synthesis, structure, and bonding of Lu7Z2Te2 (Z = Ni, Pd, Ru). Linking typical tricapped trigonal prisms in metal-rich compounds.

The syntheses and structures of and bonding in the title compounds are described and compared with those for the isostructural orthorhombic Er(7)Ni(2)Te(2) (Imm2) and other related phases. Single-crystal data are reported for Z = Ni, Pd. The condensation of tricapped trigonal prisms (TTP) into sheets and the bridging of these by separate Lu atoms into a 3D structure are described. The interlayer separation, the Lu-Lu bonding achieved, and the polar Lu-Te bonding therewith are all affected by the size and valence energies of Te. The two Te spacers also exist in capped centered Lu(6)Te trigonal prisms. In terms of extended Hückel band analyses, the overall bonding for both Lu-Ni and Lu-Te are optimized energetically, but not for Lu-Lu. The average Lu-Lu overlap populations about each Lu appropriately increase with a decrease in the number of its Te neighbors.

Journal Article↗

PubMed2004

[Arterial switch operation for transposition of the great arteries and double outlet of right ventricle with subpulmonary ventricular septum defect].

OBJECTIVE: To summarize the clinical experience on the arterial switch operation for complex congenital heart disease in recent 3 years in our hospital. METHODS: Sixty-one patients with complex congenital heart disease received by arterial switch operation from Jan 2000 to May 2003. There were 26 patients with transposition of the great arteries and intact ventricular septum (TGA-IVS), 19 patients with transposition of the great arteries and ventricular septal defect (TGA-VSD) and 16 patients with double outlet of right ventricle with subpulmonary ventricular septum defect (Taussig-Bing). RESULTS: There were 2 death among TGA-IVS cases, 4 deaths among TGA-VSD cases and 4 deaths among Taussig-Bing cases. The total operative mortality was 16%. All patients were followed up 3 months to 3 years. In all patients, the cyanosis disappeared and the physical activities increased obviously. One patients with Taussig-Bing keep moderate mitral valve reflux unchanged, 2 patients with TGA had pulmonary and aortic supra-valve stenosis with 40 mmHg pressure gradient. One patient with subpulmonary stenosis and residual VSD was re-operated 3 months later. All survivor had good heart function. CONCLUSIONS: The effect of arterial switch operation on the treatment of TGA was well accepted in this study. The procedure used in treatment on Taussig-Bing can prevent pulmonary obstruction and avoid the complication of left ventricular outflow tract obstruction caused by intraventricular repair.

Aorta↗

PubMed2004

R(6)TT'(2), new variants of the Fe(2)P structure type. Sc(6)TTe(2) (T = Ru, Os, Rh, Ir), Lu(6)MoSb(2), and the anti-typic Sc(6)Te(0.80)Bi(1.68).

The Fe(2)P structure (P62m) features two 3-fold Fe positions and both 2-fold and 1-fold P sites, and variations in occupancies of the latter pair yield the reported diversity of results. The known Sc(6)TTe(2) examples for T = Fe-Ni are herein extended to four heavier transition metal T derivatives. An attempt to synthesize bismuth analogues led to the novel inverse derivative in which fractional Te (vice T) occupies the smaller tricapped trigonal prismatic (TTP) Sc polyhedron, and Bi rather than Te occurs in the larger TTP of Sc, with parallel reversal of polarity in the bonding. The reported Lu(8)Te, which is distributed as Lu(6)TeLu(2), is the only example in which a transition metal occupies the normal 2-fold P or Te non-metal position, with corresponding large effects on the bonding. Lutetium otherwise does not form R(6)TTe(2) analogues, but the novel Lu(6)MoSb(2) isotype occurs instead. Extended Hückel calculations are presented for five examples, and the structural and bonding regularities and varieties are discussed further.

Journal Article↗

PubMed2004

Nonhomogeneous deformation in the anterior leaflet of the mitral valve.

In the mitral valve, regional variations in structure and material properties combine to affect the biomechanics of the entire valve. Previous biaxial testing has shown that mitral valve leaflet tissue is highly extensible, and exhibits nonlinear, anisotropic material properties. In this study, experimental measurements of mitral valve leaflet deformation under quasi-static pressure loading were performed on isolated porcine hearts. Biplane video images of markers placed on the anterior leaflet surface were used to reconstruct the 3D position of the markers at several pressure levels over the physiological range. A least-squares finite-element method was used to fit parametric models to the markers and to calculate the deformation over the surface. The results showed that the leaflet deformations were anisotropic, exhibiting a large nonhomogeneous radial stretch and a small circumferential stretch. This information can be used to better understand how the valve deforms under physiological loading, and to help design treatments for valve problems, such as mitral regurgitation.

Animals↗

PubMed2004

Inwardly rectifying potassium channels in rat retinal ganglion cells.

Inwardly rectifying potassium channels (Kir channels) are important for neuronal signalling and membrane excitability. In the present work we characterized, for the first time, Kir channels in rat retinal ganglion cells (RGCs), the output neurons in the retina, using immunocytochemical and patch-clamp techniques. Various subunits of Kir channels (Kir1.1, 2.1, 2.3, 3.1, 3.2 and 3.3) were expressed in RGCs, but with distinct subcellular localization. Kir1.1 was mainly expressed in axons of RGCs. Kir2.1 and Kir2.3 were both present in somata of RGCs. Whereas staining for Kir3.1 was profoundly present in an endoplasmic reticulum-like structure and Kir3.2 was strongly expressed in the cytoplasm and the cytomembrane of somata, dendrites and axons of RGCs, faint, sparse labelling for Kir3.3 was seen in the cytomembrane. Immunoreactivity for Kir4.1 and Kir4.2 was not detectable in RGCs. Whole-cell currents mediated by Kir channels were recorded in isolated RGCs and they differed from hyperpolarization-activated currents (I(h)) by showing full activation in < 10 ms, no inactivation, and being significantly suppressed by 300 microM Ba2+. Unlike in retinal horizontal cells and bipolar cells, these currents were mainly mediated by G-protein-coupled Kir3 (GIRK) channels, as demonstrated by the fact that GDP(beta)S and GTP(gamma)S included in the pipette solution markedly decreased and increased the currents, respectively. Furthermore, the GIRK channels were probably coupled to GABA(B) receptors, because baclofen considerably increased the Kir currents and the increased currents were suppressed by Ba2+. These characteristics of the Kir currents provide more versatility for signalling of RGCs.

Animals↗

PubMed2004

The structure and mechanical properties of the mitral valve leaflet-strut chordae transition zone.

Biaxial testing, histological measurements and theoretical continuum mechanics modeling were employed to investigate the structure and mechanical properties of the mitral valve leaflet-strut chordae transition zone (LCT). The results showed that geometry changes and collagen fiber angle distribution contribute to variations in mechanical properties in the LCT zone. A simple three-coefficient exponential constitutive law was able to simulate the variation in stress-stretch behavior in the LCT zone by spatially varying a single coefficient and incorporating collagen fiber angle and degree of alignment. This quantitative information can greatly improve the predictions from biomechanical valve models by incorporating regional variations of structure and properties in the mitral leaflet-chordae tendineae system. These data provide the foundation for a computational model for studying stress distributions before and following chordal rupture, which may indicate the underlying reasons for the development of valve insufficiency in patients.

Animals↗

PubMed2004

Inhibition and reversal of myocardial infarction-induced hypertrophy and heart failure by NHE-1 inhibition.

Sodium/hydrogen exchange (NHE) inhibitors show promise as potential therapeutic agents for the treatment of heart failure, but it is not known whether they can reverse the maladaptive remodeling that results in heart failure. We sought to determine the effect of the NHE-1-specific inhibitor EMD-87580 (EMD) on heart failure produced by myocardial infarction in the rat and to assess whether up to 4 wk of treatment delay results in beneficial effects. Male Sprague-Dawley rats were subjected to coronary artery ligation (or a sham procedure) and followed for up to 3 mo, at which time hypertrophy and hemodynamics were determined. EMD was provided in the diet, and treatment commenced immediately or 2-4 wk after ligation. EMD significantly reduced hemodynamic abnormalities, including the elevation in left ventricular end-diastolic pressure, and diminished the loss of systolic function with all treatment protocols. Left ventricular dilatation and hypertrophy, as assessed by heart weight, cell size, and atrial natriuretic peptide (ANP) expression, were similarly reversed to sham or near-sham levels. In addition, the increased plasma ANP and pro-ANP values were reversed to levels not significantly different from sham. Surprisingly, virtually all beneficial effects were identical with all treatment protocols. These effects were observed in the absence of infarct size reduction or blood pressure-lowering effects. Our results suggest that NHE-1 inhibition attenuates and reverses postinfarction remodeling and heart failure with a treatment delay of up to 4 wk after infarction. The effect is independent of infarct size or afterload reduction, indicating a direct effect on the myocardium.

Animals↗

PubMed2004

[Effects of P2Y receptor activation on prostatic cancer cells requiring ERK1/2 or p38 cascade].

OBJECTIVE: To determine the role of extracellular signal-regulated kinase (ERK1/2) and p38 cascades in P2Y receptor-evoked effects on prostatic cancer cells. METHODS: Highly metastatic prostatic cancer cells 1E8 were transfected with dominant-negative MAPK kinase 1 (KA-MEK1). The activation of ERK1/2 was determined by Western blot technique. The role of ERK1/2 and p38 cascades in P2Y receptor-evoked effects on in vitro growth, colony formation and in vitro invasion was detected by cell count, soft agar colony formation assay and in vitro invasion assay. The effect of ATP on apoptosis was detected by flow cytometry. RESULTS: ERK1/2 activity in 1E8-KA-MEK1 transfectants was significantly suppressed by dominant-negative MEK1 transfection. After culture of 6 days, 1E8-KA-MEK1 transfectants exhibited a growth inhibition of 71% as compared with 1E8-pcDNA3 control. Moreover, after continuous treatment with 100 micro mol/L ATP for 6 days, the growth of 1E8-KA-MEK1 transfectants was further inhibited by an additional 17.2%. Pretreatment with 10 micro mol/L p38 inhibitor SB203580 antagonized the effect of ATP-induced additional growth inhibition, suggesting that ERK1/2 and p38 pathways play an important role in ATP-induced growth inhibition. In soft agar assay, 1E8-KA-MEK1 transfectants formed smaller colonies and exhibited a 75% decrease in colony formation (as compared with control). Further treatment with ATP or SB203580 plus ATP did not show significant effect on colony formation of 1E8-KA-MEK1 cells, implying a potential role of ERK1/2, instead of p38, in P2Y receptor-mediated inhibitory effect on colony formation. In in vitro invasion assay, 1E8-KA-MEK1 cells showed a 41% decrease in passing through matrigel-coated membranes, as compared with control. Treatment with ATP could restore their invasive ability, and this effect by ATP could be blocked by pretreatment with SB203580, indicating the involvement of both ERK1/2 and p38 pathways in invasive ability of prostatic cancer cells. CONCLUSIONS: The effects of ATP on in vitro growth, invasion and colony formation of prostatic cancer cells depend on the status of P2Y receptor activation by different treatment protocols. Continuous activation of P2Y receptor results in growth inhibition and transient activation of P2Y receptor stimulates in vitro invasion of prostatic cancer cells. Both ERK1/2 and p38 pathways are responsible for these effects; but only the ERK1/2 pathway is involved in regulation of colony formation of prostatic cancer cells.

Adenosine Triphosphate↗

PubMed2004

Single photon emission computer tomography of dopamine transporters in monkeys and humans with 99mTc-TRODAT-1.

BACKGROUND: The diagnosis of Parkinson's disease is presently based on non-specific symptoms. However, radionuclide dopamine transporters imaging can provide specific diagnostic tool for Parkinson's disease. This study was designed to investigate the effects of imaging of dopamine transporters with 99mTc-TRODAT-1 in early diagnosis or differential diagnosis of Parkinson's disease. METHODS: Nine normal monkeys were used to establish N-methyl-4-phenyl-1, 2, 3, 6-tetra-hydropyridine (MPTP) hemi-Parkinsonian animal models, and they were subjected to imaging. Twenty-nine patients with Parkinson's disease, 12 age-matched healthy volunteers, and 18 age-matched patients with Parkinson's syndrome were investigated. Single photon emission computer tomography (SPECT) was performed 3 hours after intravenous injection of 740 MBq 99mTc-TRODAT-1. Striatum specific uptake of 99mTc-TRODAT-1 was calculated according to the ratio of striatum (ST) to cerebellum (CB) in dopamine transporters uptake. RESULTS: In normal monkeys, bilateral ratio of ST/CB was 2.34 +/- 0.41. After the injection of MPTP, uptake rate of 99mTc-TRODAT-1 at damaged region was much lower than that at the contralateral region, resulting in a significant difference in the ratio of ST/CB (right: ST/CB = 1.73 +/- 0.35; left: ST/CB = 1.90 +/- 0.30), especially in hemi-Parkinsonian model monkeys (right: ST/CB = 1.29 +/- 0.17; left: ST/CB = 1.80 +/- 0.33). The ratios of ST/CB were 1.57 +/- 0.17 and 1.61 +/- 0.14 for the right and left respectively in the healthy volunteers, 1.04 +/- 0.29 and 1.06 +/- 0.30 in the age-matched patients with Parkinson's disease, and 1.56 +/- 0.17 and 1.59 +/- 0.18 in the age-matched patients with Parkinson's disease syndrome. A significant difference was noted between group of Parkinson's disease, normal controls and Parkinson's disease syndrome. CONCLUSION: The results suggest that 99mTc-TRODAT-1 dopamine transporters SPECT has clinical application value in early diagnosis or differential diagnosis of Parkinson's disease.

Adult↗

PubMed2004

[Pathological observations of Fructus Schisandrae polysaccharide on anti-tumor effects in S180-bearing mice].

OBJECTIVE: To study the effects of Fructus Schisandrae Polysaccharide (FSP) on anti-tumor in S180-bearing mice. METHODS: The transplantable carcinosarcoma model was established in S180-bearing mice by subcutaneous implantation. Tumor size and histopathological changes were observed under electron microscopy by HE staining after 8 days treatment. RESULTS: Morphological changes showed that slight cataplasia and apoptosis were induced by high concentration FSP, as well as the numbers of inflammatory cells in tumor were increased and tumor cells in infiltration areas around tumor cataplasised partly. These suggested that high concentration FSP can inhibit tumor growth lightly. In addition, high concentration FSP combined with cyclophosphamide can promote the effect of anti-tumor. CONCLUSIONS: FSP can inhibit tumor growth, this effect may be correlated with apoptosis and the activation of immunocytes, but not depend on killing tumor cells directly. In addition, high concentration FSP combined with cyclophosphamide can promote the capacity on anti-tumor in S180-bearing mice.

Animals↗

PubMed2004

[Electrofusion of building coupling system for degrading anthracene and fusants' choices].

Some researches have been carried out for the electro fusion of building coupling system for degrading anthracene and the choices of fusants. During the experiments, total rate of fusion stable in alternation current frequency 500 kHz, impulse intensity 300 V/cm, impulse width 5 micros, amount of impulse 2 and alternation current intensity 20-40 V/cm were found. The resistant plate with erythromycin and ampicillin can screen the fusant of autochthonous bacterium and surfactant-producing bacterium. The resistant plate with anthracene and karnamicin can screen the fusant of autochthonous bacterium and efficient anthracene-degradation bacterium. The new fusants were found to have stable fluorescent characteristics.

Anthracenes↗

PubMed2004

[Analysis on content of Ni-Cr in gingival and blood of hares after wearing non-noble porcelain-fused-to-metal crown].

OBJECTIVE: Purpose of the study was to investigate the content of Nickel (Ni) and Chromium (Cr) ion in gingival tissue and blood, and to discuss the reason of gray line in gingival after wearing non-noble Porcelain-Fused-to-Metal crown. METHODS: 38 rabbits were selected as experimental animals which were divided into three groups: control group, group 1 (3 months) and group 2 (6 months). The content of Ni and Cr ion in gingival tissue and blood was detected by atomic absorption spectrometer. RESULTS: The amount of Ni and Cr in group 2 was significantly higher than that in other groups (P < 0.05) . There was no difference between group 1 and control group (P > 0.05) . CONCLUSION: The reason of gingival colouration might be the electrochemical corrosion. The metal ion was released in gingival tissue and blood.

Animals↗

PubMed2004

[Increased expression of Fas and FasL mRNA in peripheral blood lymphocytes in Vogt-Koyanagi-Harada syndrome].

OBJECTIVE: To evaluate the expression of Fas and FasL messenger RNA (mRNA) in peripheral blood lymphocytes and its possible role in the pathogenesis of Vogt-Koyanagi-Harada syndrome. METHODS: Blood samples were obtained from 16 patients with Vogt-Koyanagi-Harada syndrome and 19 healthy individuals from January to June, 2000. Total RNA was extracted from peripheral blood lymphocytes. cDNA was prepared from RNA with oligo d(T)(18) and M-MuLV reverse transcriptase. The expression of Fas mRNA and FasL mRNA in peripheral blood lymphocytes was determined using fluorescent quantitative polymerase chain reaction (FQ-PCR). Amplification was carried out through 32 cycles, 30 seconds denaturation at 93 degrees C, 30 seconds annealing at 58 degrees C, and 45 seconds primer extension at 72 degrees C. The final extension time was 7 minutes. RESULTS: The expression of Fas mRNA on peripheral blood lymphocytes [(1.6 +/- 2.0) x 10(6)] was significantly higher than that of the controls [(5.7 +/- 2.0) x 10(5)] (t = 4.50, P < 0.05). The mRNA expression of FasL on peripheral blood lymphocytes [(1.8 +/- 1.5) x 10(6)] was also higher than that of the controls [(4.8 +/- 3.5) x 10(5)] (t = 9.57, P < 0.05). CONCLUSIONS: A high level of Fas mRNA and FasL mRNA expression in activated peripheral blood lymphocytes is observed in patients with Vogt-Koyanagi-Harada syndrome. These long-persisted activated lymphocytes may be responsible for the perpetuation and recurrence of Vogt-Koyanagi-Harada syndrome.

Adult↗

PubMed2004

Adsorption mechanism of phenolic compounds from aqueous solution on hypercrosslinked polymeric adsorbent.

The adsorption of two phenols, namely, phenol and salicylic acid(SA) onto a water-compatible hypercrosslinked polymeric resin (NJ-8) were studied in terms of pseudo-second-order and first order mechanisms for chemical sorption as well as an intraparticle diffusion mechanism process. Kinetic analysis showed that the intraparticle diffusion process was the essential rate-controlling step. The activation energies of sorption have also been evaluated with the pseudo-second-order and intraparticle diffusion constants, respectively. Adsorption equilibrium data were well fitted by the Langmuir, Freundlich and Redlich-Peterson isotherms. Adsorption was exothermic and basically of a type of transition between physical and chemical character. The sorption capacity was higher for SA due to its more hydrophobic. Phenol has a higher adsorption enthalpy since it could form stronger hydrogen bonding on NJ-8.

Adsorption↗

PubMed2004

[Expression of pituitary tumor transforming gene, endostatin, and basic fibroblast growth factor mRNAs in invasive pituitary adenomas].

OBJECTIVE: To investigate the effect of the expression of pituitary tumor transforming gene (PTTG), endostatin and basic fibroblast growth factor (bFGF) in invasive pituitary adenomas. METHODS: Reverse transcription-polymerase chain reaction (RT-PCR) was used to detect the expression of PTTG, endostatin, and bFGF mRNA in invasive and non-invasive pituitary adenomas. RESULTS: The expression of PTTG and bFGF significantly increased in the invasive pituitary adenomas (all P < 0.01) compared with those in the non-invasive pituitary adenomas. However, the expression of endostatin significantly decreased in the invasive pituitary adenomas compared with the non-invasive pituitary adenomas (P < 0.01). CONCLUSION: Increased expression of human PTTG and bFGF, and decreased expression of endostatin may be related to the genesis of tumor invasiveness. The feasible mechanism may be related to that the increased expression of PTTG plays a role in pituitary tumor invasiveness by altering the balance of tumor angiogenesis.

Adenoma↗

PubMed2004

[Evaluation of the problems in the treatment of uveitis].

OBJECTIVE: To address the problems present in the treatment of uveitis. METHODS: A retrospective analysis was made on 154 patients (268 eyes) with different entities of uveitis, coming from all over China and referring to Zhongshan ophthalmic center from April to October of 2000. The data of these patients, especially with respect to the usage of corticosteroids and antibiotics in the referred hospitals, were analyzed. RESULTS: Corticosteroids drops, subconjunctival or retrobulbar injection and systemic corticosteroids were respectively used in 90.3% and 84.0% of these eyes, and 92.9% of these cases. Intravenous injection of corticosteroids was rather popular, accounting for 85.3% of the cases who were treated with systemic corticosteroids. Improperly aggressive treatment with corticosteroids or undue application of their eye drops was equally found in patients from county-, city- and province-level hospitals, especially in Behcet's disease, anterior uveitis and Fuchs heterochromic uveitis. Antibiotics drops, subconjunctival injection and systemic administration of antibiotics were respectively used in 97.0% and 71.6% of these eyes and 83.8% of these patients. Immunosuppressive drugs, other than the corticosteroids, were used in 6 patients only. CONCLUSIONS: Corticosteroids should be used in proper methods, dosage and duration based on the entities and severity of uveitis. It is not necessary to treat noninfectious uveitis with antibiotics.

Adolescent↗

PubMed2003

Yeast xrs2 binds DNA and helps target rad50 and mre11 to DNA ends.

Saccharomyces cerevisiae Rad50, Mre11, and Xrs2 proteins are involved in homologous recombination, non-homologous end-joining, DNA damage checkpoint signaling, and telomere maintenance. These proteins form a stable complex that has nuclease, DNA binding, and DNA end recognition activities. Of the components of the Rad50.Mre11.Xrs2 complex, Xrs2 is the least characterized. The available evidence is consistent with the idea that Xrs2 recruits other protein factors in reactions that pertain to the biological functions of the Rad50.Mre11.Xrs2 complex. Here we present biochemical evidence that Xrs2 has an associated DNA-binding activity that is specific for DNA structures. We also define the contributions of Xrs2 to the activities of the Rad50.Mre11.Xrs2 complex. Importantly, we demonstrate that Xrs2 is critical for targeting of Rad50 and Mre11 to DNA ends. Thus, Xrs2 likely plays a direct role in the engagement of DNA substrates by the Rad50. Mre11.Xrs2 complex in various biological processes.

Adenosine Triphosphatases↗

PubMed2003

Expression patterns of inwardly rectifying potassium channel subunits in rat retina.

The expression patterns of inwardly rectifying potassium (Kir) channel subunits (Kir 1.1, 2.1, 2.3, 3.1, 3.2, 3.3, 4.1, and 4.2) were studied in rat retina by immunohistochemistry, with special emphasis on neuronal expression. Except for Kir4.1, the subunits tested were all expressed on neurons in the inner nuclear and ganglion cell layers. While Kir2.1 was densely present in the cytoplasm, the staining for all other subunits was predominantly expressed on the cell membrane. Most subunits, but not Kir 2.1 and 2.3, were present in the outer and inner plexiform layers to different extents. Kir4.1-immunoreactivity was found in astrocytes wrapping retinal blood vessels, in addition to the Müller cell endfoot. The differential expression of the Kir subunits suggests the diversity of physiological roles these channels may play.

Animals↗